Telegram CEO Pavel Durov is still in custody in France and is being investigated by the national cyber crime unit and the national fraud office, a French police spokesman said on Monday, Paralel.Az reports citing Reuters.

A police spokesman told Reuters that Durov is under investigation by the national cyber crime and fraud offices for failing to cooperate over cyber and financial crimes on Telegram, a messaging app and social media. He is still in custody, the spokesman said.

Durov, 39, was arrested at Le Bourget airport outside Paris shortly after landing on a private jet late on Saturday.

Durov, a 39-year-old billionaire cast as "Russia's Mark Zuckerberg" has dual French and United Arab Emirates citizenship. Estimated by Forbes to have a fortune of $15.5 billion, Durov said in April some governments had sought to pressure him, but the app should remain a neutral platform and not a "player in geopolitics".